Hydraulic control valves and systems, which are widely applied to hydraulic drive and control systems, are used to control direction, pressure and flow of fluid and significantly influence various areas of industrial and mobile equipment, in which hydraulic transmission systems are used.
Traditionally mainstream hydraulic control valves are various types of so-called “plated connection” hydraulic control valves adopting international standards (such as 4 ports directional control valves and sandwich valves using the standard installation surface conformed to ISO4401/CETOP, 2 ports pressure control valves using standard installation surface conformed to ISO6264/5781, flow control valves using standard installation surface conformed to ISO6263, and so on).
From the principle of technology, this kind of products can be called “single element” products. The so-called valve systems currently are combinations of various types of valve circuits and systems with “single element” valve products according to the control requirements, based on experience (multi-functional control circuits and systems of, such as directional, pressure, flow and combination thereof). In so many valve circuits/loops and systems, the combined loop based on 4 ports directional control valves, that is, so-called “4-way loop”, is one of the most important and common loops. These 4-way loops with 4 ports directional valves, kinds of throttles and flow valves (usually with check/one direction elements), pressure valves (usually with check elements), almost takes up more than half of all of the circuits.
The schematic of traditional four-way hydraulic circuit in FIG. 1 shows a typical complicated four-way circuit based on 4 ports directional control valves. Because of history, “single element” valves only have one function, but have different internal and external structures, they not only are seriously disperse in function, structure and form, but also, with development of the technology they are used inconveniently.
By the judgment of “the principle of minimal fluid resistance” in hydraulic loop design proposed by “Hydraulic Resistance Theory”, these traditional valve circuits and systems consisted of “single element” valves, especially the most representative 4-way circuits consisted of 4 port direction control valves, have many defects and unreasonable structures.
In addition, from the technical aspect, the most traditional “single element” hydraulic circuits perform the so called “manifold block(plate)” “valve block”, or “integrated block”) pattern based on installation surfaces, according to the requirement of application, manufacturing and installation. When hydraulic circuits and systems have to change or partly change designs or frames, this kind of circuits and manifold blocks (valve blocks or integrated blocks), not only related valve elements, valve circuits, and design and layout of its system, but also the design of manifold block (valve blocks or integrated blocks) have to be changed, which means that the connection, installation and process of the system have to be changed. So, any change in circuits will cause correspondingly a change in all the chain of supplement. The changes will, not only increase costs, postpone the time limit, require many new designs and drawing documents and increase possibilities of errors, but also make the management complicated. Then, this will make the management can not fit the rapid development of technical environment, and is bad for the mode of modern product development, advanced manufacturing and fine management.
Actually, the widely used connections and integrated patterns based on installation surface try to improve the performance of module and configuration by using traditional stack and connection block modular integrated pattern. The efforts have made some progress in components and circuits, but, in general of smaller size, especially in middle size between 10 mm and 32 mm, did not obviously overcome above mentioned defects.